This lecture starts with a lengthy discussion of definitions and the different ways of formulating definitions. He mainly focuses on definition as genus and species identification. He also discusses definitions that are focused on the part to whole relationship, on a thing’s structure, or on a thing’s function or use.
The rest of the lecture is divided between looking at Aquinas’ definition of law and then exploring the concept of nature. Aquinas defines law as “as an ordering of reason, promulgated by the person in charge of a community, for the common good.” Koterski explains each aspect of this definition: that law is an ordering of reason as opposed to an ordering based on will or power and that law has to be publicly disclosed and so on. Four different types of law, as articulated by Aquinas, are then explained: Eternal Law, Divine Law, Natural Law, and Human/Positive Law.
In his discussion of the definition of nature, Koterski follows Aristotle in claiming that we can discover an entity’s nature by observation and reflection. A things nature is the “internal principle of something’s development and typical activities.” It is the way something characteristically develops and acts.
In an interesting discussion of what is meant by natural, Koterski notes that the natural isn’t just average or the normal. It is what constitutes the full mature healthy individual member of that species. He discusses the “privilege of the normal case” as the case we use to describe the typical and characteristics traits and behaviors and to contrast this species with another. He also importantly argues that the normal case is not used for species demarcation, that is, for determining species membership. The normal case is used for comparing the natures of species, but it is not the sorting principle. In this way, he hopes to avoid the pitfalls of claiming that fetuses, senial, comatose, etc., are not humans because they are incapable of being rational.
Koterski closes the lecture with a brief discussion of human nature. Following Aristotle, he defines human as the rational animal. We belong to the larger group of animate objects, but what makes us specifically different is our broad power of rationality. He also discusses personality in addition to rationality, something I hope and expect he will explain more in subsequent lectures since what he meant by this was not clear. He didn’t mean personality in terms of “she has a nice personality.” I think he intends this to mean that humans have other important qualities and facilities besides rationality—and that these qualities are part of our personhood.